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Wet season rainfall outlook for Hawaii


Summary of dry season
2010-2011 La Nina event ended in late spring

  • Helped extend the wet season into early June

Dry season had a late start but hit hard in August and September
Statewide: Drought worsened after spring improvement
Big Island: “Extreme drought” (D3 category in U.S. Drought Monitor) returns to leeward Kohala and southern Ka‘u District

  • Mainly affecting livestock and some fruit orchards

Maui County: “Severe drought” (D2 category) returns to leeward Haleakala
Kauai and Oahu: “Moderate drought” (D1 category) developed in late September and early October

  • Lihue Airport: Driest September since 1975

Windward rainfall frequency near normal but daily totals are below normal
“Severe drought” has affected portions of the State of Hawaii continuously since June 2008

Outlook for wet season (October through April)
Climate Prediction Center (CPC): La Nina has returned but forecasted to be weaker in 2011-2012 than the 2010-2011 event

  • Drier than normal through October
  • Wetter than normal January through April/May

La Nina precipitation forecasts have considerable uncertainty
Recent wet seasons with weak La Nina

  • 1995-1996 and 2000-2001 are most recent examples
  • 1995-1996: Near median overall precipitation
  • 2000-2001: Drier than normal overall

Drought recovery more likely on Kauai and Oahu.
Some drought recovery expected on the Big Island and Maui County but full recovery may be elusive due to intensity and longevity of existing drought conditions

Wet season preparedness
Clean gutters and drainage ditches
If you live in a flood-prone area, identify your evacuation routes ahead of time
Plan for more rainy weather impacts

  • Increased road travel times or possible detours due to flooding
  • Outdoor activities may be postponed, canceled, or adjusted

The wet season always brings increased potential for lightning strikes

  • Be prepared for possible power outages
  • Move indoors during a thunderstorm
  • June 4, 2011 storm produced more than 22,000 lightning flashes in 30-hours over and near the main Hawaiian Islands

Monitor media, NOAA Weather Radio, Internet sources for changes in weather conditions

On the Web:

NOAA National Weather Service Honolulu HI:

NOAA Climate Prediction Center:

U.S. Drought Monitor:

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